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DIY: 1998 528i S.A.S Pierburg Air Pump Maintenance and Rebuild Info

76K views 47 replies 22 participants last post by  bluebee  
#1 · (Edited)
DIY: 1998 528i S.A.S Pierburg Air Pump Maintenance and Rebuild Info

* Look up how S.A.S. works, basically at cold start, the S.A.S. Air Valve opens and the Air Pump injects extra air into the exhaust system to reduce polution.

* When Air Valve fails in OPEN position, exhaust flows backward into the Air Pump with water vapor, destroying the Air Pump.
Then no extra air is injected into the exhaust system at cold start, the ECU will register a P0410 OBD-II Code (S.A.S. Fault) because the O2 sensor does not sense a change in readings as programmed.

* Best is to prevent damage to Air Pump: Every 80-100K miles:
- replace the Air Valve as there is not much lifespan remaining.
- replace the vacuum hose, use only thick-walled vacuum hose to prevent hose collapse under vacuum suction.

I also own a 1998 Volvo V70, and the Volvo Air Pump is also made by Pierburg, so the idea is the same. The BMW and Volvo Air Pumps are very similar (almost 95% the same). Actually with this info, you can apply to any European Cars (VW, Audi, MB etc.) with this setup of Pierburg Air Pump.
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DIY Instructions:

1- To replace the Air Valve. This is a 10-min job.
- Air Valve is #14 (It varies from year to year), Gasket is #15. Vacuum Hose (use any thick-walled vacuum hose that matches size)
http://www.realoem.com/bmw/showparts.do?model=DD53&mospid=47585&btnr=11_1539&hg=11&fg=45

- New Pierburg Air Valve is $107 at EACTuning:
http://www.eactuning.com/parts/product_details/11727540466

- Make sure you don't over-tighten the 10-mm nuts.
Look it up but I think the torque is 10 Nm, basically snug and tug a bit!

*** Now if you read Step #1 above and change the Air Valve and its hose every 80-100K miles, you don't need to read further. Info below is for those who want to tackle the Air Pump should it become defective.

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2. To REMOVE Air Pump for rebuild:
- Front Passenger Tire off
- Passenger Front side on Jackstand
- Front Wheel Vinyl Fender off (8-mm screws)
- Using a Long Extension and Ratchet, remove the 3 screws (10-mm) holding the Air Pump BRACKET. Do not touch the 10-mm nuts holding the Air Pump to the BRACKET because you will regret you did that!

- Disconnect Hose Clamps and Electrical Connector and the Air Pump will come out.

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3. To REBUILD Air Pump.
Rebuild only if you are short of budget and has the skills/desires to do it. With proper tools, it is easy.
Without proper tools ---> order new Air Pump!
Information is included here for those who have the skills and tools.


- Follow the instructions in the attached pictures:

- This is from my 1998 Volvo V70 but it is the same for BMW E39, use 6 paper clips to wedge the flange and pull it out:
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Here is the BMW E39 Air Pump:

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Tips/Tricks:
- To drill out the Six (6) rivets holding the Air Pump, use a 5/32" drill bit, the rivets will come out nicely.
- Use liquid paper to mark alignment of Air Pump housing to make re-installation easier (don't you want your life easier?...:))
- To re-install, use #8-32, 1.5 inches long nuts and bolts. You need a tocal of Six (6), Hardware store sells this package for $0.99.
- After the nut is tightened (don't over-tighten the nut), I use a pair of vice-grips and crimp the protruding threads on the bolts to prevent the nuts from working loose; kind of locking the nuts in (I did trick on my Volvo one year ago and the nuts hold tight).

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#2 ·
I just spotted Item #11 (Basically the Air Filter for the SAS Air Pump) has never been discussed in this forum. I have never paid attention to this "Piece of Crap" until now. It is in the second picture of my post above (next to the word "Air Flow").

BMW PN 11721744340

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I guess it is out-of-sight-out-of-mind kind of thingy.
 

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#24 ·
DIY: 1998 528i S.A.S Pierburg Air Pump Maintenance and Rebuild Info
S.A.S.

Noun1.SAS - Special Air Service - a specialist regiment of the British army that is trained in commando techniques of warfare and used in clandestine operations (especially against terrorist groups)
*******> ********>
Small Astronomy Satellite, a series of NASA satellites

Secure Attention Sequence or secure attention key, a method to invoke a computer operating system's attention, usually signaling it to show the log on screen

A self-anchored suspension bridge is a suspension bridge in which the main cables attach to the ends of the road, rather than to the ground via large anchorages. The design is well-suited for construction atop elevated piers, or in areas of unstable soils where anchorages would be difficult to construct.

School of Arts and Sciences

Sex And Suspense

Sealed Authentication System

Seven Abominable Sins

Satellite Audio Service

Seismic Acoustic Sensor

Solid Axle Swap

Steering Angle Sensor (it must be this one!)

Yes? No?
 
#3 ·
Very informative, thanks as always cn!
 
#8 ·
Nice post cn.

Helpful for WHEN mine goes.

I replaced the Air Valve, gasket and vacuum hose as preventative when I got my touring (easy DIY) ... hopefully it'll help the Air Pump last a little longer. :)
Smart man!

If you replace the Air Valve religiously every 80-90K or so, the Air Pump lasts virtually forever b/c the Air pump runs only 1-2 minutes and only during COLD start.

It is exhaust gas (when the Air Valve fails) that kills the Air Pump so by preventing exhaust gas from coming into the Air Pump, you significantly extend its lifespan.
Plus when the Air Pump goes bad, you have to replace the Air Valve anyway, costing way more.
 
#16 ·
Someone asks me about the special puller to remove the Impeller.

Without the special puller, you can still pull the Impeller using this home-made method:

1. Using a Vice-grip and appropriate nut, bite both the collar and the nut so they become one unit.

2. Then use appropriate bolt to remove the collar.

Basically this is a "home-made" puller!

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#17 ·
Update:

For those of you who want to rebuild the Air Pump's electric motor, use bearing with this size 6 mm x 19 mm x 6 mm (ID x OD x thickness). It is commonly used for roller blade, believe it or not.

Choices are:
- SKF 626 ($8 + shipping on ebay)
- Timken 36pp ($12 on line)
- No name 626RS. Go to ebay and enter: "626RS" or "6 x 19 x 6 bearing" ($7 incl. shipping on ebay)

HTH
 
#18 ·
I take it that you were able to separate the impeller using your special technique w/ the vise grip ? IF so, where did you find the appropriate size nut to work with the visegrip? I had no luck separating the impeller. The Vise grip trick requires too precise of a nut to be able to clamp the two parts with even force. I even welded the nut to the visegrip,
but when I went to crank down on the bolt to separate the impeller, the vise grip slipped out of the head of the impeller, and that left me with a set of visegrips I could no longer open out again. :mad:

Unless I come up with another idea,
this is one part that I'm not going to DIY.
 
#20 · (Edited)
I wrote this DIY for those who want to rebuild the Air Pump using new bearing. The reason for the above DIY is that this electrical motor for the Air Pump is very very and very difficult to find.

UPDATE:

- I opened the Pierburg Air Pump and did an autopsy on it:
The Electrical Motor is Johnson HC971(2)LG-101.

I contacted Johnson Motor and they only sell this motor to Pierburg and not to the public:
http://www.johnsonelectric.com/mediando/index.php?IdTreeGroup=179&IdProduct=604

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Spec for Johnson HC971(2)LG-101 is:

Size: Diameter 52 mm x Length 85 mm: shaft Ø 6.005 mm

-----------------No load---------Stall-----------Max efficiency----------Max power

Speed (rpm)..........6400..................-.....................5600.........................3200

Current (A).............1.20...............53.65................8.02...........................27.43

Torque (mNm)..........-................915.92...............119.07.........................457.96

Efficiency (%)............-...................-......................66.67...........................-

Power (W).................-...................-..................... 69.50........................153.63

----------------
After a lot of internet search I found a motor that hobby-lobby people use Graupner 900 BB motor to power their toy air plane that has virtually identical spec as Johnson Motor.

So we need someone to try this "guinea pig" for the rest of us.

The good news is that: in contrast to Johnson electrical motor (which is made in China for Pierburg!), the Graupner 900 BB motor ($59) is made in Germany:

http://www.hobby-lobby.com/speed_900_bb_torque_12v_2581_prd1.htm

Specification for Graupner 900 BB motor

Nominal voltage 12 V (this is the same as Pierburg Air Pump)
Operating voltage range 6 ... 40 V
No-load rpm 6500 min***8211;1 (this is the same as Pierburg Air Pump)
No-load current drain 1,1 A

Current drain at max. efficiency 8 A

Current drain when stalled 54 A (this is the same as Pierburg Air Pump)

Max. efficiency without gearbox 71 %
Length of case, excl. shaft 85 mm (this is the same as Pierburg Air Pump)
Diameter 51,5 mm (this is the same as Pierburg Air Pump)
Free shaft length 15 mm (this is the same as Pierburg Air Pump)
Shaft diameter 6 mm (this is the same as Pierburg Air Pump)
Weight 645 g
 
#21 ·
For those of you who want to see the anatomy of a typical Pierburg Air Pump, here it is. I just took the picture today. You can see that the motor shaft is 6-mm and is press-fit into the impeller. So with some WD-40 the day before, vice-grip on the stub of impeller and a 5-mm drift, you can tap the motor out:

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#22 · (Edited)
Pulled my air pump out today to clean it out in my 99 528i. Didn't even bother pressing the impeller away from the motor, perhaps later. The motor runs, and even ran a couple days ago on startup (though most of the time it did not run before this cleanout). Sounds like a jet engine, so I'm pretty sure the bearings are failing. My 97 comes on and is nowhere NEAR that loud.

I also pulled the EGR valve out and wiped it down, shot it out with throttle body cleaner etc. Curiousity got the best of me and I blew into both ends. While it was still warm, I could manage to force a little air through both openings. When it was cold, it was not allowing ANY air to get through.

After cleaning and reassembling the pump, including cleaning the foam filter (need a new one, or some foam material to make my own), I reinstalled it, put the EGR back on, replaced the vacuum tube to the EGR (it was rotted and had a hole in it), even wrapped a thick layer of electrical tape on the tube from the pump to the EGR (had a small crack, I will be replacing it shortly), started it up, listened to the pump whine, but the CEL light did not go off.

I went to Autozone to have the CEL reset, but they were already closed. :mad:

Is the EGR supposed to be closed when cold? If so, how is the pump supposed to be blowing air through it? Is it spring loaded?
 
#26 · (Edited)
OK. Done googling. I updated the E39 acronym update with SAS.
Definition of SAS = secondary air system as in S.A.S Pierburg Air Pump

Here are the google references:
- cn90 How To Rebuild Pierburg Air Pump (P0410 Code) (explains SAS)
- MotorAge Understanding secondary air fault codes on European vehicles (explains SAS)
- cn90 volvo DIY: How to rebuild pierburg air pump (explains SAS)
- unitedbimmer Secondary Air System
- bimmerforums E39 Secondary Air Pump -- Fault Codes P0491, P0492 (explains SAS)

But, most SAS references assume you know what SAS stands for:
- cn90 volvo SAS air pump rebuild
- volvo air pump fix tutorial
- cnn 1998 528i S.A.S. Pierburg Air Pump Maintenance and Rebuild Info
- cnn DIY: Troubleshooting S.A.S. and How to Replace the Famous Fuse # 107!
- DIY Secondary Air Pump replacement

BTW, cn90 seems to be the world-wide reference for SAS repairs based on my googling; and his annotated photos are phenomenal!
 
#30 ·
I just cracked open my e36 air pump - the valve must have failed long ago... the poor exhaust-rusted motor had tried so hard to keep spinning that it melted the windings into a copper blob.
A few findings:

pulling the impeller with a pin/hammer and vice-grips did not work.
What did work really well: The ID of the hub is a perfect size for a 1/4-20 tap. I tapped the exposed hole, dropped in a short pin, kept the hub from spinning with vice-grips, and threaded in a 1/4-20 bolt. The hub came right off.

Since the motor was literally melted I ordered a speed 900BB motor from Graupner as an experiment. Guess what? Its too long. I think the 85mm case length measurements above must have included the shaft? I peeled back the Graupner label and there was a Johnson Motor P/N sticker under it!!
It also seems to perfectly fit the description of the HC971. So.. If the E39 air pump really has an 85mm long motor, then the 900BB is probably a direct replacement.

Since I'm into this already I'll try squeezing in the longer motor. Its not going to be pretty but the front end seems a perfect fit.
 
#31 ·
....Since the motor was literally melted I ordered a speed 900BB motor from Graupner as an experiment. Guess what? Its too long. I think the 85mm case length measurements above must have included the shaft? I peeled back the Graupner label and there was a Johnson Motor P/N sticker under it!!
It also seems to perfectly fit the description of the HC971. So.. If the E39 air pump really has an 85mm long motor, then the 900BB is probably a direct replacement.

Since I'm into this already I'll try squeezing in the longer motor. Its not going to be pretty but the front end seems a perfect fit.
Please keep us posted with the Graupner motor.
Take some pics and post them!

What is the exact measurement of the Graupner motor vs the Johnson Control Motor?
Also what is the JC PN underneath the Graupner sticker?
 
#35 ·
I bought the Graupner motor and successfully (?) installed it

OK, I took the risk and bought the Graupner Speed 900 BB motor. I figured it was worth the $75 risk to keep from spending $400 for a new one or $150 for a junk one.

I ended up buying the motor directly from Graupner USA rather than Hobby-Lobby, here's the link:

http://www.v-eastonline.com/products/Speed-900-BB--12v..html

The reason I bought the motor from Graupner was because they had it in stock. I originally ordered it from Hobby-Lobby but it was on back order and after 2 weeks, they still couldn't give me a definitive date as to when I'd get it. I then ordered it from Graupner on 24 September and I received it on 30 September. A bonus was that it was about $1.50 cheaper buying direct from Graupner.

The motor actually arrived at my door at about 10:00PM and by about 10:04PM I noticed the same thing as Wyattm3, the Graupner motor is about 3/4" longer than the original motor. With my exuberance dashed, I decided to sleep on the problem and tackle it the next day.

Here's what my wife and I ended up doing:

(FYI #1 - All of my part name references will be from the exploded view picture in cn90's excellent post on 12 June 2010)

(FYI #2 - My car is a 2000 528i and, aside from the end cap, my air pump is identical to cn90's)

(FYI #3 - In my exuberance I didn't take a single picture of what I'm about to describe ... I know, I deserve to be humanely destroyed ... sorry)

1. I removed the bracket from the business end of the Graupner motor, 4 philips head screws and it's off. It's useless for us and reveals 4 slots used in #2 below.

2. Although not actually named in the picture, there's a little sqare-ish rubber pad attached to the business end of the Johnson motor. This comes off and attaches in exactly the same manner to the Graupner motor. It's a perfect fit, right down to the raised notches on the rubber pad fitting into the slots revealed in #1 above. If you have trouble getting it to seat, try rotating it 90 degrees.

This rubber pad seems important for 2 reasons. First, it fits into an indention at the bottom of the pump housing and serves to center the motor in the pump housing. Second, it probably provides resistance for the torque of the motor, keeping the motor from spinning in the pump housing.

3. After much fiddling, we determined that the plastic ring, spring and rubber washer would not be going back into the pump as the additional length of the graupner motor just wouldn't allow it. So, my wife cut about 6 or 8 strips (about 3/8" x 3") of dense foam packing rubber we had laying around, packing peanuts may work, you'll have to improvise here just as we did. Anyway, we packed the strips between the motor and the pump housing. The packing was tight enough that it kept the connection end of the motor centered in the housing and it kept it wedged in the housing pretty well for the next step.

4. Using a large C clamp, we pressed the impeller onto the shaft of the motor. Again, with respect to the OD of the shaft and ID of the impeller, this was a perfect fit. The shaft didn't go completely through the impeller, then again, neither did the original. Anyway, I just pressed it in enough to where the 2 outer casings were fitting snugly together.

Whatever you use to press the impeller to the shaft, just make certain that you're ONLY pressing on the shaft that protrudes about 1/4" out of the connection end of the motor. The whole arrangement is sort of awkward and shifty and it's easy to slip over and start pressing against the motor casing rather than the shaft, the motor casing isn't flimsy but, it isn't meant to provide this type of pressing resistance and you'll probably damage the bearings so, be careful here and work slowly.

5. Place the rubber ring onto the connection end of the motor, again, this fits exactly as it did on the Johnson motor and fits perfectly as well. At first we were going to discard this as well, however, we found that it is VERY useful in keeping the leads from touching the casing and causing a short circuit. You definitely need this piece.

6. Since this is a DC motor, it matters which one of the connectors is (+) and which one is (-) as this will determine which direction the motor turns and they don't mark it on the motor because the user's application will determine the desired direction of rotation. If you get this wrong then the pump will suck (literally) rather than blow and we definitely need this pump to blow. Therefore, at this point, it would be wise to determine which of the connectors is which. You'll need some sort of DC power supply, I used my trickle charger, however, a direct connection to a car battery will work too. As long as you know which of your power supply leads is (+) and (-) this will be easy. Looking at the assembly from the impeller end, you want the impeller to rotate CCW. When you have the leads connected such that the impeller rotates CCW then, mark the leads as (+) and (-) and go to the next step.

Whatever you do, DO NOT try and energize the motor with power from a household outlet, the power at your outlet is AC, not DC, and it's 120V. You will destroy this motor in milliseconds AND probably injure yourself and/or others AND probably burn your house down if you try to use a household power supply.

7. Now it's time to get the electrical connector attached. Because the motor is too long, it doesn't simply snap back into place. In fact, about as close as you can get it to the motor still leaves it about 1/2" from snapping back into place. So, to solve this problem, using an exacto knife and a small hacksaw blade, my wife (because I'm lethal to myself and others with these tools) removed about 1/2" from the notched ribs along the outside of the pump housing that the electrical connector originally snapped onto. This is where a picture would have been useful, again, sorry.

Now that we solved one problem, we created another, now there's a substantial gap between the pump housing and the electrical connector. To solve this my wife used more of the dense packing foam and cut out a donut roughly the same diameter as the pump housing (actually a little bigger) which we used as a gasket/gap filler. Packing peanuts definitely won't work here, you'll need something continuous and waterproof in order to protect the connections from the elements. Only time will tell how our solution will work. If your splash shield is in place then, this shouldn't take too much abuse so, we'll see.

Anyway, once all of this was ready we put the foam "gasket" in place then I connected the brown wire to the connector I marked (-) and the red wire to the connector I marked (+) then we muscled the clips on the electrical connector over the previously cut ribs.

8. I then put the end cap back in place and used plastic zip ties in place of the rivets to hold everything together. I was too lazy to make a trip to Lowe's to get the screws so I used the largest zip ties that I could shove through the rivet holes. I use zip ties as much as I do duct tape!

9. Just to make sure Frankenstein was alive, I attached the pump to my power supply and much to my great astonishment, it worked! The pump was alive!! I had previously marked the outside of the electrical connector as (+) and (-) just for this purpose, I suggest you do the same.

10. Since he's much more limber than me, I had my son reinstall the pump onto the car and then, since it was cold, had him start it, again, much to my great astonishment, it worked! The pump was alive!!

11. Wait for your codes to clear OR clear them yourself and pray they don't come back.

12. The end.

This is actually the second time I've typed out this post. The first time I typed it, it was at this exact point that my computer started making an annoying rattling noise. I've got a gimpy cooling fan and a good kick in the side usually quiets it right down ... except this time the computer fought back ... it rebooted. Bye, bye huge post. I guess that'll teach me to kick my computer so, I'm off to buy a cooling fan. I decided to retype this post because I wanted to give back to the community which has been so helpful to me, I hope this has been helpful to someone.

PS: My codes never cleared after 10 cold start cycles so I reset them, I only have P1421/P1423. After 2 post-reset cold starts the codes came back. It seems my diverter valve is toast too. I hate this S.A.S. The dealer wanted $160 for the valve and $15 for the gasket, after several hours of searching the internet, I found them for $75.95 and $5.95, respectively, with free shipping and no sales tax at: www.alloembmwparts.com

Meanwhile, while I'm waiting for the diverter valve I ordered just last night, since I don't need the car at the moment, I've removed the diverter valve from the manifold but left it connected to the vacuum hose, cold started the car and used my garage compressor to blow air into the manifold while the pump runs and blows aimlessly to the atmosphere. I'm trying to simulate a properly operating S.A.S. I've done this twice now and the codes haven't gone away. I hate this S.A.S. This probably won't work but, it's worth a try. While this is going on I can look into the diverter valve and see that it isn't working and yes, I checked for a vacuum at the hose and it's definitely there.

I'll let you know if all of this effort eventually pays off. Did I mention that I hate this S.A.S.?

Good Luck!!

Greg